The present invention relates generally to DSP interface circuits employed in disc systems and more specifically to a flexible DVD-DSP interface circuit that may be programmed to support multiple communication interfaces between different DVD DSP's and DVD decoders.
The term "disc system" as used herein is directed to any system (e.g., optical, magnetic, etc.) that accesses data held on a rotating disc. Optical disc-drive systems include read-only compact discs, laser discs, DVD's (also referred to as "digital versatile discs" and "digital video discs," and including DVD-ROM, DVD-Video and DVD-Audio), as well as their writable counterparts (e.g., CD-R, CD-RW, DVD-R and DVD-RAM). Additional information regarding DVD technology may be found in J. Talyor, DVD Demystified, McGraw-Hill (1998), which is hereby incorporated by reference in its entirety for all purposes.
A typical DVD disc system (also referred to herein as a "DVD system") includes the following elements: (1) a disc access mechanism for spinning and reading data from a disc, (2) a digital signal processor ("DSP") for translating data read from the disc into a format for processing by the remainder of the system, (3) a decoder for converting data provided by the DSP into audio and/or video signals and (4) a microcontroller for controlling the operation of the system. Typically, in a DVD system a DSP and its associated audio/video decoder(also referred to herein as a "DVD DSP" and "DVD decoder," respectively) are discrete semiconductor devices or chips.
The "communication interface" between a DSP and a decoder in a disc system consists of control and data signals being exchanged according to specific operating parameters (e.g., active high or low signals, rising or falling-edge signal triggers, etc.) as dictated by the DSP. A DSP interface circuit facilitates such communication.
Because the communication interface between a DVD DSP and a DVD decoder is not standardized, a DVD decoder may only support one DVD DSP in accordance with its communication interface. This causes the DVD decoder to be locked in with a particular DVD DSP which inherently limits its usefulness. To support DVD DSP chips employing a different communication interface, a single DVD decoder will require external, specialized logic thereby increasing the cost of the DVD disc system in which it resides.
Thus, it would be desirable to support multiple communication interfaces between a DSP and associated decoder in a disc system and, in particular, to support multiple communication interfaces between a DVD DSP and associated DVD decoder without requiring additional, specialized logic uniquely tailored for each particular interface.